1. Field of the Invention
This invention relates to an injection molder probe, which has heating means for heating a hot runner portion as fused resin path and also intermittently heating a gate portion to opening and closing the gate, and also to a runnerless injection molder provided with the same probe.
2. Brief Description of the Prior Art
FIG. 13 is a sectional view, partly broken away, showing a sharp heat generator (hereinafter referred to as probe) for constructing a hot runner, as disclosed in Japanese Utility Model Publication S60-28569. With reference to this Figure, the well-known injection molder probe structure will be described.
Designated at 2 is an outer cylinder (i.e., body portion ) made of a heat-bearing metal, for instance stainless steel, at 6 an inner space in the outer cylinder, and at 6a an axial bore formed in the metal outer cylinder 2 along the axis thereof and hear a sharp tip portion 3. In the bore 6a, a heat generator 7 comprising a coil of a heat generating wire is disposed, and it is externally furnished with power through leads 11a and 11b for locally heating the sharp tip portion 3. A separate heater 8 is accommodated in the inner space 6 of the metal outer cylinder for holding a synthetic resin in the runner in a fused state at all times.
In a runnerless injection molder, a probe 1 having the above construction is mounted in dies. A gate portion heating to the cavity is locally heated with the sharp tip portion 3 for instantly fusing the synthetic resin that has been cooledly solidified to hold the gate closed, thus opening the gate, whereby the fused resin is injected into the cavity in an injection molding operation to obtain a molding. By cutting or restricting power supply to the heat generator 7, the fused resin in the gate portion is solidified or half solidified, thus closing the gate.
However, with the runnerless injection molder with the above prior art probe 1 mounted in the dies, the heat generator 7, which is for intermittently heating the sharp tip portion 3 of the probe 1, and the heater 8, which is for heating the metal outer cylinder at all times, have to be separately power supply controlled, thus posing the problems of requiring an complicated, large size and expensive power supply unit. In addition, it is considerably difficult to provide a reduced size probe.
This invention seeks to solve the above problems inherent in the prior art, and its object is to provide an injection molder probe and a runnerless injection molder, in which a simplified structure heater for intermittently heating the tip portion of the probe and a heater for heating the body portion of the probe are furnished with power from a single power source.